ATLANTA (AP) — A low-flying police helicopter searching for a runaway boy hit a power line pole before it plummeted to the ground and exploded, killing both officers on board but leaving those on the ground unharmed.

Federal authorities were investigating what caused the chopper to crash into power lines along on a busy city street. Electricity was knocked out to nearby homes and businesses in an area filled with shopping plazas, fast-food restaurants and a gas station.

The 9-year-old boy was found wandering on a city street a couple of hours after the crash late Saturday night, Atlanta police spokesman Officer John Chafee said Sunday. He ran away after being scolded by his mother.

The two officers were identified Sunday as pilot Richard J. Halford, 48, of Lithia Springs, who had been with the department for 26 years, and Shawn A. Smiley, 40, of Lithonia, a tactical flight officer who joined the department two years ago.

Atlanta Police Chief George Turner praised the two officers as public servants who died honorably in the search for the missing boy. Both men were fathers. Smiley had three children under the age of 10.

"Every day, they provided air support for our officers, assisting in major events and searches for suspects and missing persons," Turner said in a news release. "Their value to our citizens and our officers on the street is incalculable."

The families have asked for privacy, and trust funds have been set up at Wells Fargo bank locations to help them, said Atlanta police spokesman Carlos Campos.

Their deaths shook not only the police force, but the entire city.

"It's sad. It's tragic ... for someone to lose their lives trying to find a kid, trying to keep another family together," Rodney Christian, 22, said as he and more than a dozen others looked at the scene in the early morning darkness Sunday. Christian lamented the tragedy and thought of his 1-month-old baby.

"It makes me want to rush home and get back to my kid."

The wreckage of the OH-6A helicopter had already been moved as investigators worked to piece together what happened, said Eric M. Weiss, a spokesman with the National Transportation Safety Board.

Part of the helicopter's landing gear had to be removed from the cables with the help of the power company.

The NTSB investigators were going over maintenance records and had talked to witnesses.

"They saw the aircraft, they heard the aircraft, and then they saw a flash of light when it hit the pole and then it crashed into the roadway," investigator Ralph Hicks said.

Records with the Federal Aviation Administration showed the helicopter was a Hughes OH-6A manufactured in 1967. The Hughes has historically been a military workhorse.

Atlanta police referred questions about what caused the crash to federal investigators.

Bystander Darryl James, 42, said he had gone with a companion to a check-cashing store Saturday night when he heard the helicopter flying overhead and thought it was rather low.

"The tail end went down and then there was an explosion," James said. He said he tried to get close to the wreckage. "As soon as I got close enough to it, poom! It exploded."

James said people are often waiting at a normally busy bus stop near the crash site, adding, "Thank God nobody was out there."

After the crash, fire trucks and police cars with lights flashing converged on the area, blocking surrounding roads. Police put up yellow crime scene tape and kept bystanders so far back they were unable to see the crash site behind a small rise.

Atlanta Mayor Kasim Reed said he was saddened by what he called a "terrible accident."

"We mourn these two brave men and offer our deepest condolences to their families and loved ones," Reed said in a statement.